This invention relates to a lift for loading and unloading a truck, and more particularly to a lift mounted on a freight collection/delivery truck at a rear end of a load-carrying platform.
Recently, distributors in Japan have established a distribution system in which furnitures and other properties to be moved at the time of house-moving are transported by being accommodated in special boxes or crates having castor wheels on their bottom sides and having dimensions of about 1,100 mm in width and length and 1,900 mm in height, and have developed such a system into a whole-country distribution network in Japan. The same distributors also have established and used a whole-country network of a separate small-lot delivery system.
However, vehicles for separate small-lot delivery must be so short in overall length as to be able to enter into a narrow passage, since they are used to deliver small packages to individual homes.
On the other hand, vehicles specially used for house-moving require a large lift (table lifter) for loading or unloading the above-mentioned special boxes and therefore have a large overall length.
It has been impossible to provide a large lift for small vehicles for separate small-lot delivery, because the performance for such a purpose is thereby impaired.
House-moving vehicles having large lifts are inconvenient when used for small-lot delivery because the operation interferes with the lift. Thus, small packages are loaded or unloaded through a rear door opening without using the rear end lift. Also, house-moving vehicles are inferior in quick-wheeling performance and their use is undesirable under present traffic circumstances, i.e., a serious traffic jam and strict parking restrictions, since a speedy collection/delivery operation is required for separate small-lot delivery.
That is, a load lift is used to move a heavy thing between the ground and a load-carrying platform, and is indispensable for house-moving vehicles frequently used to transport heavy things, but it is not necessary for vehicles for separate small-lot delivery.
For these different types of vehicles, however, different garages and drivers are required, and one distributor separately uses different vehicles in the same area, so that the traffic is aggravated.
Load lifts for use with the above-mentioned house-moving vehicles include types A to G shown in FIGS. 9(a) to 15(b). These types of lifts will be described below by using the same reference characters with respect to the same functional components.
In the case of the types A, B, and E (FIGS. 9(a), 9(b), FIGS. 10(a), 10(b), FIGS. 13(a), 13(b)), a lift table 103 is moved in a vertical direction by a parallel link 104 or a lift column 105, and is swung upward to be set in an upright position at the rear or in front of rear doors 102 of a load chamber or rear body or cargo space 101 when the lift is retracted. This lift has a drawback such that things cannot be loaded in or unloaded from the load chamber 101 unless the lift table 103 is operated to be set in a horizontal position.
In the case of the type C (FIGS. 11(a) and 11(b)), a lift table 103 is retracted by a parallel link 104 (not shown) to a position under the deck when the vehicle travels. Therefore, if a length L of the lift table 103 is increased, a dimension ROH (rear overhung) between rear tires 106 and a rearmost end of the rear body and, hence, the overall length of the vehicle is increased.
The same can also be said with respect to the type D (FIGS. 12(a) and (b)) having a deck corresponding to the ROH.
In the case of the type F (FIGS. 14(a) and 14(b)), a lift table 103 is retracted by being folded under the deck when the vehicle travels. Therefore, the retracting operation is complicated. In particular, if the lift table 103 is large and heavy, it is difficult to handle and the retracting operation is dangerous. Also, the ROH cannot be reduced as desired because of the existence of a parallel link 104.
The type G (FIGS. 15(a) and 15(b)) is a variation of the type A and has a lift table 103 which is retracted by being swung downwardly to be set in a vertical position below rear doors 102. If the size of the lift table 103 is increased, the ground clearance H of the end of the lift table 103 at the time of traveling becomes insufficient. The size of the lift table 103 is therefore limited.